Drying-kiln.



P. vv. TURNER.

DRYING KILN.

APPLICATION FILED SEPT.20. 1915.

Patented Apr. 3,

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fon'iuuesien of eppliesimi serial No. 31,4%, le. 3u.

' 'Serial le e. el.

Be it knee/ii has l, Pelis-sf W. TURNER' :i eiizen Qi: flie Huil/ed Stilles. and s sesident of lilyn'dus, lilew Mexico. have iiweniecl Cerwin new snel useful lmplovements im @Wing-lilies, si' which the fellowing is specification.

This applicaties is e eontinuaties of my' pxevious applicelien Serial Number Bllll. ileel Julie El., 1915, for drying kiln, w'icli modifications enel improvemenzs thereon.

My invention is especially :wlapled to dry ing kilns im: lumber, bul. il." is espelile` of use for {liying bi'ieles snel nher purpeses. llt will lie sullieieiit herein le explain elle inves:

'tien applied te a, lumber kiln.

Kline lieifeeoiiore used; for lumber are oli jeetioneble foi' one or more of thel'ollowing ressens: ineemplelbe er inefficient drying; est cessive checking 0r splitting of lumber; "csse--lierdeniug due to redeposil; el? mois`- ure upeii lslie lumbse, These diiieulties are.

el lumber in e. sliolzeiw lime, lies 'relueed Checking' miel spilli/ing lo e iimflel (legiee and lies eimiely avoided essehsidening, :is

eempee Wih @xfliiiery kilns of subastas iially lie same Hommel eepecily.

The ehameteristies enel sdvenlisges el my invention will be further described, lieleei'lei so fai' es may be necesseiy to enable per sens skilled in elle are le undeislencl the seme. is eouieezion with s, les'ileil desei'ipllioneif the accompanying eli-swing., Wliieli sliewe @ne typical ferm of kiln previmisly usecl and else shows en exempliiying en v boflimens of my invention.

Figure l is e l0ng1tudinel-verticsl section ilirougle e kiln embdymg; my iiiveniien. Fig. 2 is en eilsrggel5 Oleizul el" the semen igj iss. longgiluflinal versieel section of e lipeeiles'timi el .u Passivi.

typical eid. leem smi Fim. lis s detail of i "she seme. is s. fece View el the regulating; fans.

le previously eppmved. kilns, of which Fig. 3 one typical eseieiple7 there is e. Coldl air Chamblee@ :il'mve which is a liet Chamber se dej/img chamber H. These cimmliers sie inelosefl'in 'wells which we usually el imei; Wien suitable provision for liest msulstlon amel alle lliymg chamber is suit- -ebly roofed with propel lies-.l insulation. Al;

elle ends l sind 2 ciones im the entrance sind exil; iespeeiiely of ems eeeiying lumbei' properly i'eeleeel is' permit the message el? sir lJelwe *elle busreis. The details @if the building', deel-s mesme fel* hamelliig the lumloei1 inte enel om, @if che kiln, are nos of spesi-.il importance and will not be nel tieulerly eleseiieefl. lliese arranges .is may be my suizsble ones well known in she ses. the Cold. eil Chamber and elle drying cimmliei* is e grid. 0f steam pipes S sind steam is usually slipplieel lo these pipes 'from s. main aft 3' smi diselmiggecl et l. se that elle circulation eti steam iii the heating coils sul)- staiiiislly corresponds Wish "elle ceurse el? the luiiibei? tlm-@ugh "elle kiln.

All is supplied le Jalie cold chamber' through s.. plualiey el lues 5 (shawn in from, elevation Fig. fl) which @Grassillieste with en olileng eenduit (l spell si?, the discharge end 7 which is seme clismiice from the resi' Suppoi'lell by suitable beams between lli the lei'igiili .eil the kiln. This conduit 6 is provided Willi nei'm'w ausvers-e openings 8 :il intervals in the sop. lelie purpose oli which is lo discharge siii* upward si; inkervels. All the front @nel ei' lille roof upen (me 01* beth of liesicle Wells is e. chimney 0i: steek 9., eenlieining elle discharge lues connected with disclisxge openings l() usually arranged diagonally in the Walls Uf ille drying chamber., the ciiseliergeepeninlgs emi steel; les' one side ef 'lle kiln being; e eerlyliewn in Fig; 3. The cubic eepeeity oi elle flis charge stl-Lele is usually eensileisbly ,Greater than that eltlie supply conduit, 6 and 'its lines.

lill

lber near the exit end 2.

asdescribed fail to dry lumbergasquickly or as completely arid uniformly as desired; that they frequently accumulate moisture upon the roof which drops back upon the lumber, also that there is a, tendency for moisture extracted from the lumber near the entrance end 1 to be redeposited -uponlum- This redeposit of moisture by dripping from the roof or directly from the air in the kiln causes the effect known as case-hardeningin many'.

cases. There is' also an undue amount of checking and cracking of the boards. The principal cause of4 these difficulties is believed to belthe fact thatair does not circulate properly" in the kiln. Instead. of passing through the slits 8 in the top of conduit 6 to any considerable extent, the principal amount of air introduced into the cold charnbeil issues at the discharge end 7 under the influence of the draft from the Most of the -cold air therefore -duit to the stack causes air containing moisture drawn from the lumber near the end 1 to circulate toward the discharge end 2. Being already` loaded with moisture this V air does not have proper capacity to with draw moisture from the lumber near the discharge end, and on the contrary, there is a notable tendency for moisturel to be redeposited upon the stacks of lumber which are soon to be discharged at the end 2. There is also frequently an accumulation of moisture upon the roof and this-drips back upon the lumber. This effect isA noticeable in lumber discharged, because it is frequently found that some of the lumber, and

especially that in the center of the stacks, is quite-'moist even when the outer lumber ofthe stackris comparatively dry. Owing to the high temperature in the drying chamber it is impossible to make exact tests of the circulation, but'the theory given to account forthe deficiencies of the kiln is based upon the closest possible observation and accounts in a reasonable, and it is believed in a correct, way forl the results obtained. The circulation consequent upon the conditions described is also believed to produce undesirably variable temperatures in the drying.,r chamber and th variations of tem perature are supposed to be responsible for the checking and splitting of the lumber which isl often noticed. With kilns in use up to the completion of my invention it is o ten found to be dilicult, even with the expenditure of liberal' amounts of fuel, to maintain a sufficiently high temperature `in the' drying chamber and this is believed to be-largely due to the `fact that an unnecf cept with respect to the circulation system.

In place of t e air supply means formerly used I provide usually a single intake flue or ipe 11, usually of round section and pre erably located substantially centrally of v the Width of the front wall of the cold air chamber. This flue terminates at 12, a short distance within the cold chamber. Within this flue and `vusually `near the intake end thereof is a regulating device 13, which in a preferred form consists of an automatically acting rotary regulating device. More particularly described this is, in the most improved form of the invention I have up to the present time devised, a rotary bladed fan, as shown in enlarged section in Fig. 2. The shaft ,or spindle 14 of this fan is parallel to the axis of the flue and is supported Y by suitable bearings 15 carried by suitable supports within the flue. It has been found usually desirable to permit the fan to run as freely as possible and for that purpose easy running cone or roller bearings may be used'. lf it is found by experiment that such free running bearings are not necessary or desirable, plain bearings or other Suitable mounting for the fan or equivalent regulating device may be employed.

At the discharge end of Hue 11 is a delector or diffuser 16, lconsisting in this embodiment of a shallow cone or pyramid of sheet metal having its apex located slightly within the discharge end of the flue. A small substantially annular discharge space is thus afforded between the end of the flue and the face of the diffuser. This diffuser may be suitably supported in-any convenient way in the position shown and details of the supporting means are therefore not particularly described,

In place of the discharge stack ordinarily employed I provide for a kiln of ordinary dimensions, a single discharge flue or pipe,

mainz/e preferably larger than the discharge end. ln the present embodiment somewhat, but in a satisfactory workings einH b odiment of the invention l haveemployed the' following dimensions: intake flue, diameter l2 inches; exhaust ilue, diameter 28 inches. lln the present embodiment this exhaust regulating device or fan isl mountu ed to freely rotate in'bearings .similar to those used for the intake fan. El satisfactory det-ail of fan construction consists in connecting the tips of the ldiapbonally arrangs; blades to. a ring of'- sheet metal. This ring runs very close to the inside of the '5.- respective flue.

'of alrln theL "pension of water 'top of the chamber causes a vigorous dlschar'e of mmsture When the kiln constructed as described is properly charged-With green lumber and heat supplied through the steam pipes, ein

pension of air in the dryinp; chanber causes an exhaust through flue Il? and the move ment of air through the flue causes the :tan 19 to revolve. Air enters the cold chamber through flue 1l and causes the fan 13 to revolve at such speed asto supply the proper amount of air-to take the place oi the air exhausted through flue 17. The entering' air strikes baille plate 16 and is to a considerable extent didused throughout the cold chamber and rises through the grid of steam pipes in accordance with the draft created by the heat therein. A large part, and probably a major part, ofthe entering air however passes upward through the part of the steam vcoil nearer to the end 2 of the lriln. The current olf the circulation of air is in dicated by broken lines and arrows in Fia". l, the lheavier portion of the circulation lines indicate the probable'course of the major part of the air. There isa large expansion `rying chamber due to the heatv supplied thereto and this expansion is probably considerably augmented by the exvapor drawn from the luln ber. This expansion, it is believed, causes a noticeable pressure, especially near the ll and this pressure laden air through the exhaust liuc and the exhaust fan 19 rotates rapidly in accordance' with the discharge of air through it. llt is also believed that the properly selected capacity of the intake liuc ll., combined. yu'itli the coming and regulating ell'ect of the inthe discharge liuc moisture to collect mg chamber and ceives an ample current it causes the t'an taire fan 13 andthe retarding and diffusing 65 effect of the baffle plate 16, duced pressure in the' cold chamber and in the lower part of the hot air chamber. Probably the pressure in these parte ofthe kiln is decidedly below atmosphere and' Where this effect-is obtained the evaporatingr capacity of 'the hea* supplied is markedly augmented. lt is supposed that the circulation from the intake to the exhaust flue creates .a reis practically direct at all the parts, or most 5 all parts, ot the lriln, Without any consid erable return currents or eddiesand that this circulation is approrimately proportional to the yproper requirements of the lumber in, dillerent parts of the kiln. found 'that there is little or no tendency for upon the roof of the dry-- practically no tendency for moisture to he redeposited upon the lumber. .lt is also found that lumber comes from the ldisclrarge end 2 of the kiln in a. remarkably dry condition with unusual freedom from checks or splits. This indicates that thp'lumber, Whichobecomes drier as it is lt is moved `from the entrance to the exit end oi the lriln in the progressive loading and dief charge of lumber, is progressively dried and that the lumber about to be discharged reof dry hot air` which removes from it the last trace of moisture. rlfhis complete drying; of the dischz'irged lumber Without tliaa'edeposit of moisture thereon indicates clearly that there is such circulation as to substantially eliminate recondensation.

it is also found that this lrilnfis romarin ably free from the effect of atmospheric conditions, suchas moisture, Wind pressure and direction. etc. liVhile'each ofthe rotary fans evidently revolves in accordance with the air pressure imposed upon it, the results obtained from the riln indicate that these fans have a mutual and coiiperative baliiingz; and regulating c'lect, which is not obtained in kilns having unrestricted or manually controlled supply and discharge lines. The impact of air directly against 'the blades evidently checks the speed oli' the air while to rotate and diverte the air tangentially and this tangential or whirling' movement of air in the intake pipe is possibly responsible to' a lai-,age extent for the proper diffusion. of air in the cold chamber and its proper lcirculation in the drying; chamber without return currents. The discharge fan 19, in addition to its other iunctions, .is also believed. to have a considerable',

veffect in battling heat and retaining' heat I through this kiln than is ordinarily the case,

lrelatively moderate; but if the flu'es 11 and 1 7 were of sufiicient area to admit suiiicient air for all conditions, the draft even at the low temperature, except for the regulating l fans 13 and 19, would be sufficient to pass through the kiln more air than could be efiiciently heated. The result would be ineiiicient drying .because a relatively large volume 'of air at low temperature has an inferior capacity to extract moisture from the lumber.' But the employment of the automatic regulating devices 13 and 19 offers suitable resistance to the relatively moderate draft and reduces the. air -supply to the quantity that4 may be efficiently heated at the relatively low temperature of the kiln.-

As thetemperature builds'up the draft .in-

creases-and the regulating fans by revolving faster permit a greater amount of air to pass through the kiln; but the fans at the same time exert a proportional regulating effect and prevent the passage of so much air as would be admitted without them; in other words, the ouantity of air issuitably varied at different temperatures, butis at the same timel regulated so that `.on1y so much air is passed through the kiln as may be eiectivelyheated, and this` air in turn acts most eiiiciently in extracting moisture from the lumber. f

It has been found that under substantially the same conditions@ much more uniform temperature a 'itghi'gher average temperature is obtain' y"with my invention than has been previously the case. In one 'test run 33 temperature readings were made at suitable intervals of a kiln embodying my in; vention and a kiln otherwise similar except that it has a decidedly larger heating surface and -ordinary circulation system. These readings showed an average temperature in my kiln of 213 and in the other kiln 195 with the same steam supply. This temperature differehce is of more value than the mere percentage difference, because at the higherl temperatures an additional few degrees has a relatively greater eect 'than the same number of degrees at lower temperatures.

`I have given above .what I believe is the correct theory of operation of my invention, bui.` owing tovthe Working conditions 'and especially the"tem'p eraturev within the hot chamber, positive circulation tests cannot be made and the theory of operation is deduced largely from results noted. ever the exact operation of the device may .be, there is' a very decided improvement in drying efiiciency as compared with previeusly used devices and this improvement 1s, in a few words, undoubtedly due to improved and efiicient circulation afforded by v' the coperation of th devices described.

The fan blades employed are usuallyr quite Wide and overlapping and set at a very obtuse angle to the, axis of the iue; but these conditions may vary in some cases and different types of fans or rotary valves be employed where desired.

I have described one supply and one disor other equivalent regulating devices'may charge flue for a kiln and this will probably be suitable in kilns of standard size, butin improved results from those formerly ob-` tained would be noted if the exhaust regulating device were omitted while retaining.

the intake regulating devices as described. I claim: 1. In a drying kiln, the combination of a' below, heating pipes between the chambers, an air supply for the cold chamber, baiiling means therefor and a discharge flue passing through the roof of the drying chamber near one end thereof and terminating in an enlarged inlet below the top of said chamber..

2. Ina drying kiln, the combination of a drying chamber, a cold air chamber therebelow, heating pipes between the chambers,

'drying chamber, a cold air chamber therean a1r supply flue for the cold chamber, a.4

rotary regulatin device therein, a diiusing device for said ue, a larger discharge Hue for the drying chamber and a rotary regulating device therein.

3. In a drying kiln, the combination of a drying chamber, a cold air chamber therebelow, heating pipes between the chambers,.

a supply Hue for the cold chamber, a rotary* bladed regulating device therein, adischarge fine for the/drying chamber and a rotary bladed regulating device therein. n

' 4. In a nylug kiln, the combination of a drying chamber, a cold air chamber therebelow, heating pipes between the chambers, a supply iue for the cold chamber, an automatic rotary bladed regulating device in the flue rotating in a transverse plane therelil? 7 .,'Tf v, ei, e. beimg devine :it the rem end Mie e, siipply. iue for 'the mici. eii @immbeia e bei'` Miei' e roiery iiiadei i-eguieting deyiee in seid dieeheg'e fine.

drying cheminer', e wifi air chsimbei' there below; heating pipei; iieween the ehembei's., e siippiy passage *the cold ein; eimmiie eremy biecieii :veg Eating rie'viee in seid fille, e diseiiefge iiue for 'the drying ehem-- bei' teimiiiziiing tile-weite iieiow iii-e iep @if ih@ chembei', the iiiiieiie emi of seid dieeiieige iiue being large? 'the exhaust end, theree-E :md e. reimy iiieeied dwing" device in seifi dieciiefgje fine. v

7. The eem'bineiyi @if a e eed eil cimmiiei" eine' means between the e? f: mipy fiile for .the @eid am membei e, isehmrg'e Hue fer ie drying; @amber-ente. l chamber beiew the iep llheireei emi e regulating devine/a e iegifuleie of air* from. said niej/im; ehemifei'.

S. The eembimie f ef :i defying; ehembei', :i com eil: cheminee iheiebeiew, iieming ineens between the eiiamibeis, :i Supply Hue 'fer ilhe eel-ri siii' chamber pi'mifiefi Wi'h e beiie pietje iieiow the @op heree dass iieecriioefi., the Chamber? a eei. viii! efmbei T.M- -yei m heating Differ; iece'lefi o imei, eii i@ iie'sees i'iaeiii ene eiieiiniiei' te the @them en Supply i ii iieiieyge @eid un 'L ne L en: e5 si.

1 @e im sup eminem :i isen erge '1 viese dessmiiiefi, @he .iii 1i', ai (miei mii imm r' ne c;

a iiii fe v ice u" i fami.

jacent i0" the discharge end of said Hue., e

discharge finie ifm' the drying chamber, and e i'eziily ieguiating dei/'ice in seid discharge frime,

a @lisier of the class deeeiibed, he 'eomiiiiieien of e fii'yin; chamber., e @eid l s.. Y, im' Guembe? thereundei, a layer; of heating 6. in a iyiiig kiim the eombiiieiien 0f e pipeeieceted in posion 'ie heee eil es ii; from eme Cim-neem:VV to 'the other., au" supply means im the @eid eu chamber' eempriemg ineens for reguieting the admission e of faire emi diffusing @through die Gold chambei siii supplied theiveio, a, discharge flue foi the drying chamber, and; i'egule'eing mesme theieiii ee'iuetzed by 'the air passing through said .time

Lili, in a. diiei' for lumber er the like, the cembineien of :i drying ehaimbeif? en siii* chamber theeimfiem heet-ing' pipes, mi siii. suppiy iie. :for iiie mi eifieiifiiiera e. ailieehai'ge iue fm die di'yiiig chamber, anni e eguieiinp; im iii seid ciiseiierge Hue :ictueteci by ihe iseheigefi eil'. e

i5. in :i ciiiei: for iumhf ea* the like, the combinetien ef a` fifying eeeiriieer9 am air chamber 'liereimdei' heating pipes, en eil* :supply fiile for the chamber, e isc'herge Hue for "ehe drying chamber., and e iveguieb ing fan in seid eil euppiy fiile actuated by the enteiring ein 16. in :i [hier mfiumbei or the iik@ the c emb nation mi e drying chamber, am siii' chamber thereunder, heating; pipes.,i en en.

supply Bue for 'the air? chmnbeig'e discharge fine fer' the fii'yiiig; chembexg mid e reguiei mg ien m the iseimge fine ifegemg on en substantially 'pemile with the fiile.

1"?. im a. iixfier :for 'iumbeif ci' ihe iiie, the eemiiinei-ien of e Tying eiiembe, en siii chamber 'hereuieden heating f Le, nii" Supp'iy Hue :for Jie aix diemlm e iieeifgeige iiue im the drying cimirfibei7 and e regain@ ing: iii the eil suppiy 'Hue i'eteiiig en an exim Subsmniinily pai-und 'with the fiile.

5.8. 1in zi (hier foi iumbei el' the iike, the eembinzatimi of :L denying; chamber, ein air chamber theifeimder, heating pipes, em eireupipiy fine for iie air chamber, e, discharge 'Fine im the drying eheinbein, and a reguim'iim?" fen iii he fiifseiieiige ini ereteting en mi eine .Cniiisiaiiziey 'perfiiiei ith the ne, Seid iieiiiff impeieii eixiy by the air miielt 1 Le 1 l fiile for eeifi mi wim :mi Mime:

iue for the drying chamber, and a regulating fan in the air supply ue rotating on. an axis'substantially parallel with the lue, said fan. being impelled only by the entering air. i

combination of a dryingv chamber, an air chamber thereunder, heating pipes, an air supply ue for the air chamber, a discharge -ue for. the/drying" chamber, a regulating fan in saidsupply Hue and a regulating fan in.` said discharge fluefsaid fans being impelled only by their respective air currents. f Y

21. In a drier of the class described, the combination of a drying chamber, an air chamber thereunder, heating pipes located 20. In a drier for lumber or the like,l the in position to heat air as it passes from the air chamber to the dryingchamber, an air supply flue for the air chamber, it discharge 2O Hue for the drying chamber, and regulating means inone of said passages actuated by air `passing throu h said flue. i

v ERRY W. TURNER. 

